Tick-borne diseases represent a significant source of mortality and morbidity in the U.S. Although Lyme Disease is the most prevalent vector- borne disease, two additional diseases, Babesiosis and Ehrlichiosis are transmitted by the same tick vector and share the same host reservoir. These diseases are often misdiagnosed or undiagnosed and better assays are needed to confirm infection and monitor the effectiveness of therapy. In the course of the Phase I studies, we propose to develop a sensitive and specific PCR based assay for Babesiosis which can be used in early diagnosis of disease and for monitoring therapy. The performance of this assay will be validated on confirmed Babesia-infected patients and on normal controls. The format of this assay will be compatible with PCR assays for the other tick-borne diseases. This will permit us to adapt this test to a multiplex format for all three of the newly described tick-borne diseases: Babesia, Lyme and Ehrlichia. The I,yme PCR assay is already developed and the Ehrlichia assay is under development. Issues of sample preparation, compatibility of amplification conditions and detection formats which can detect and differentiate between these organisms will be an important consideration. PROPOSED COMMERCIAL APPLICATIONS: A PCR test for Babesiosis will be useful in confirming early infections and monitoring the effectiveness of therapy. Ultimately, (in Phase II) a multiplex PCR assay for simultaneous detection of Borrelia burgdorferi, Babesia microti, Ehrlichia chaffeensis and E. equii (agents of Lyme Disease, Babesiosis and Ehrlichiosis, respectively) will provide a cost effective, highly sensitive screen for all three tick-borne diseases in a single sample.